A capo is a device used to shorten the string length on guitars and other musical instruments, thereby facilitating upward transposition without altered fingering. The term has European roots: “capotasto,” from Italian, “capo” meaning “head” and “tasto” meaning “tie, fret, or key.” In French the capo is called a barre, and in German, capodaster). Originally this term denoted the nut of a fretted instrument such as the lute or guitar. The term was first employed by G. B. Doni in his annotazioni of 1640. The term “capo” is now used to describe a device used to shorten string length, thereby facilitating upward transposition relative to the fret board without altered fingering.
According to the Sterner Capo Museum (http://web.telia.com/˜u86505074/capomuseum), the first capo was invented in the mid 1700's. Both the yoke capo with screw and the wooden Spanish capo cejilla were invented in the late 1700's. The yoke capo looks substantially the same today, and the Spanish capo is still in use by Flamenco guitarists. On English guitars at that time, the capo was attached through holes in the neck by a small carriage bolt tightened by a wing nut.
The first U.S. patent on the capo was U.S. Pat. No. 7,279, entitled “Guitar Head,” which issued in 1850 to James Ashborn. As shown in FIG. 1, the Ashborn capo was tightened by an eccentric roll (k) on the back of the neck (j). Referring to FIG. 2, U.S. Pat. No. 390,612, entitled “Capodastro for Guitars,” which issued to George D. Moffat on Oct. 2, 1888 describes a capo including a C-shaped mounting member (B), a pressure bar (D) which is hinged or pivoted to the C-shaped mounting member. The pressure bar is self-adjusting and is free to tilt about its point of pivotal suspension so that it can properly depress the strings regardless of the capo's position on the guitar-stem. The Moffat capo further includes a cam lever (C) which is eccentrically pivoted upon the C-shaped mounting member to urge the pressure bar against the back of the neck, thereby compressing the strings. The pressure bar may be provided with a pad (a) of cork or any other suitable material so that the pressure bar does not injure the strings. An alternative embodiment includes a bearing plate operated by an adjusting screw so that the capo may be clamped to the guitar neck.
Two capos still in use today include the Bill Russell capo and the Jim Dunlop capo. The Bill Russell capo is the subject of U.S. Pat. No. 1,788,636, entitled “Capo Tasto” (FIG. 3). The Russell capo includes a rubber pressure bar (2), which presses against the strings of a stringed instrument, a rigid reinforcing plate (1) which is positioned inside of or on top of the rubber pressure bar and to which the rubber pressure bar is secured, an elastic strip (5), a portion of which is secured to a first lug on the rubber pressure bar at one end extending over the top of the rubber pressure bar, and secured to a second lug on the rubber pressure bar. The Russell capo is secured to the stem of the stringed instrument by wrapping the remaining portion of the elastic strip about the bottom surface of the stem. The tension on the elastic strip is maintained by a plurality of eyelets (7) positioned on the elastic strip to which a set of pins are coupled.
The Jim Dunlop capo is the subject of U.S. Pat. No. 3,185,012, also entitled “Capo Tasto” (FIG. 4). The Dunlop capo includes a channel of a roughly U-shaped cross-sectional contour (16) molded from plastic, the side flanges which are arranged to diverge slightly and have beveled end edges. A non-elastic cord (26) is coupled to a cam lever (42), which is aligned perpendicular to the longitudinal axis of the stem of a stringed instrument on which it is placed and which secures the capo in place on the stem of the stringed instrument. Depending upon the thickness of the neck of the instrument, disk-shaped beads (44) are placed in corresponding recesses 28, and the device is tightened around the strings when the lever 42 is flipped down into the U-shaped channel.
The first patented plastic capo is described in U.S. Pat. No. 3,823,247 (FIG. 5). This capo includes a pressure bar (1), a bowed clamp member (2) hinged to one end of the pressure bar, and a coupling which interengages the other, unhinged end of the pressure bar in order to secure the capo to the guitar. The pressure bar has a comb-like part (8), the teeth of which are closely spaced and adapted to press on the strings of the instrument. The disadvantage in using this capo is that a musician must use both his hands to change from one fret position to another fret position. The advantage of this capo is its aesthetic qualities in that it is practically invisible when placed on a stringed instrument.
As might be expected, there are specialized capos for specialized guitars. One specialized guitar, the Dobro®, has been around since the mid 1920's. The Dobro trademark is now owned by the famous maker Gibson. Guitars of this type, built by independent guitar makers, are referred to as resonator, or, resophonic, guitars. FIG. 6 is a drawing of a classic Dobro guitar.
Resophonic guitars arose out of a need for a louder acoustic instrument, able to compete with the trumpets, saxophones and banjos that dominated popular music in the 1920s. As the story goes, George Beauchamp, a Los Angeles guitarist, took his vision of a mechanically amplified instrument to John Dopyera and his brother Rudy, Slovakian immigrants who had already patented several improvements for banjos. John Dopyera perfected a design utilizing three aluminum cones, Rudy suggested a metal body to enhance amplification, and the National tri-cone resonator guitar debuted in 1927. John Dopyera left National in 1928 and began developing a more affordable wood body guitar with a single cone and a spider-like bridge base. He introduced his new invention by the end of 1928 under the name DOBRO®—a combination of Dopyera and “brothers.”
Dobro guitars, like some slide guitars, are typically played on the musician's lap. Since the strings are spaced a considerable distance from the finger board, traditional clamping-type capos either will not work, will damage the instrument, or both. Thus, specialized capos were invented. Although some of the capos do extend around the back of the neck, most models do not and instead ‘float’ on the strings.
One of the first commercially produced floating capos is the Huckabee capo, developed in the early 1980s. With this design, a thin, round bar with plastic tubing, pulls the strings up towards a heavy, square bar by means of a screw and a wing nut. Along the bottom side of the square bar there is a routed grove to give it two distinct edges against the strings and the strings are pulled into that grove. The round bar is the Beard capo, designed by Paul E. Beard in 1985. Referring to FIG. 7, the square brass bar 702 is wider and lower. Instead of a routed grove, this capo has a bone edge 704 and a leather pad 706 to mute the strings behind the capo. Tightening is nevertheless carried out with a nut 708 coupled to sleeved bar 710 biased away from bar 702 with spring 712. A further development, shown in FIG. 8, was to replace the wing nut with an eccentric lever 802 in a capo reportedly made by Liberty in the early 1980s.